Telephone system



May 17 1927. 1,629,008

E. R. SMITH TELEPHONE SYSTEM Filed June 2 9, 1925 2 Sheets-Sheet l l l QI i i K I ax l OFFICE A May 17 1927.

E. R. sM|TH TELEPHONE SYSTEM 2 Sheets-Sheet 2 Filed June 2 9. 1925 JNMQ Patented May 17, 1927.

iinirsn stares sereni" oir-ries.

IER/MY R. SMITH, OF MAPLEXVOOD, fbi-ETH JERSEY, ASSGNOB TO VJESTERN ELECTRIC COMPANY, INCORPORATED, OF NEVI YORK, N. Y.. A COBEORATION O F NEVI YORK.

TELEPHONE SYSTEM.

Application filed June '29, 1925. 1Serial No. 40,287.

rl`his invention relates to telephone systfins and more particularly to improvements in two-way straightforward toll line systenis.

5 In toll line systems generally it is necessary to provide toll line equipment to handle different kinds of traffic, such as through connections, repeater or delayed operators connections7 and service for :these various types of connections in both directions over the same toll line.

It is an object of this invention to provide a greatly simplified two-way straightforward toll line circuit arranged for use lin 5 systems requiring these various kinds of traffic.

Another object of this invention is to provide such a tivo-way straightforward "toll line circuit that may also function satisfactorily with different types of through connecting circuits, such as a connection inciuding a ringdovvntoll line, a switching,` trunk oi' a built-up connection including one or more other twoway straightforward '-5 toll line circuits of the same kind.

To attain these and other objects of the invention, there is provided in accordance with one feature thereof means for preventing); false signaling when the straightforll ward toll line circuit is connected through la special opei'ators position lsuch as a repeater or delayed operators position. In case the cali originating operator, i. e., the one originally connected with the straightforward 35 toll line circuit for the extension of a connection therethrough, disconnects before the special operator, false signals are prevented 'from being sent back over thetoll line to the incoming end thereof for it is evident that i ordinariiy, a signal would vbe transmitted to provision of means in the two-way straigl'itforward toll line circuit whereby in a built up connection, which includes one or more lsiich straightforward toll line circuits in series, complete switchhook supervision from the called subscribers station is effected, i. e., if the called subscriber operates his switchhookyto recall the originating operator, a signal at the outward end of the straight-forward toll line circuit in the connection responds.

Another feature of the invention is the provision of means in a two-way straightforward toll line circuit, whereby in built up connections or connections involving but a single Straight-forward toll line disconnect signals are simultaneously operated in the straightforward vtoll line circuits involved and at any circuit connected ito the last. straightforward toll =line circuit in the connection, when the originating operator disconnects. Anothei` feature of the invention is the provision of means in a two-Way straightforward toll line circuit whereby, if a connection intended for a special operator has been transferred trom the inward op erators position to this special operators position, a tone is 'transmitted back to the call originating operators position until the special operator answers the call.

` rEhe invention has 'been illustrated in the accompanying drawings, in which Fig. l shows the circuit arrangement at one end of a two-way straightforward toll line with a portion of a standard cord circuit at the position o f an operator originating. a cail; rFigs. la, l", and l show respectively a ringdown toll line, a switching trunk and the outgoing end of another straightforward toll line to which type' of connectingcircuit the calls incoming over the toll line #i in Fig. l maybe routed; Fig. 2 shows a circuit arrangement a-t the opposite end of straightforward toll line shown in and port-ions of the various types of connectingcircuits whereby the toll line may be eX- tended beyond 'this point. such as a ringdown toll line, shown in Fig. 2a, a switching trunk, shown in Fig. 2b, and the outgoing end of another rtraightforward toll line shown in Fig. 2".

Referring now to the drawings in general, toll connections may be extended from an originating operators position GB by inserting plug 1 into a multiple jacl; 2. of a straightforward toll line equipment at an office A, through the toll line proper T leading to the straightforward toll line equipment at an oflice B, where at an inward operators position 1B the connection may be extended by insertion of plug 100 into jack 101 to a ringdown toll line 102 or into jack 103 of a switching trunk 104, or into jack 105 of another straightforward toll line 106. If the call is intended for a special operators position the connection may be extended from a jack such as 107 to a repeater operators cord, or from a jack such as 108 to a delayed operators cord. On the other hand, if a connection is desired in the opposite direction, i. e., from oice B to oflice A, the connection may be extended from an originating operators position in the office B. The operator may insert her plug into jack 109 to connect with the toll line T to office A and from there the extension may then be made in the same manner as the extension of a connection from office B beyond, i. e., through plug 5 at the inward operatorsY position 1Bl to the various types of connecting circuits or through jack 7 or 8 to special operators cords.

To fully understand the functioning of the invention, as represented in these drawings, it is deemed sufficient to describe in detail the extension of a connection in one direction only and first, how the straightforward toll line circuit illustrated operates when a call originates through the operators position OB and extends through the toll line T to a ringdown toll line 102 or a switching trunk 104` or another straightforward toll line circuit 106 and, second, how it functions if the connection is extended from the toll line T to a repeater or delayed operators position through jacks 107 or 108.

Referring then to the drawings in order to extend the connection from the originating operators position OB, the first action will be to insert plug 1 into jack 2. A circuit will then be completed as follows: .trein battery, winding of relay 11, winding of marginal relay 12, sleeve contacts of plug 1. jack 2, upper armature and back contacts of relay 1S, partly through. the upper high resistance winding of relay 14 to ground, but primarily through the lower low resistance winding of relay 14 to ground at the lower armature and back Contact of relay 13.

The operation of relay 14 closes au obvious energizing circuit for relay 15 at its upper armature and front Contact and the operation of relay 15 closes an energizing circuit for busy signal 16 associated with jack 2, busy signal 17 associated with jack 7 and busy signal 18 associated with jack 8, as follows: battery, upper outer armature and front contact of relay 15, windings of signals 16, 17 and 18 in series to ground. The operation of relay 14 also closes a circuit for relay 20, as follows: battery, winding of relay 20, upper armature and front Contact of relay 14 to ground. The operation of relay 20 disconnects the inward end of the toll line leading to the inward operators position 1B at this oflice and terminating in plug 5, and connects the toll line to jacks 2, 7 and 8 at the outward operators position 0B and the repeater and delayed operators positions respectively. The operation of relays 14 and 20 close a circuit for the operation of relay 21 follows: battery, upper outer armature and front contact of relay 20, upper winding of relay 21, lower outer armature and back contact of relay 22, upper armature and front contact of relay 14 to ground. Relay 21 in operating provides a connection for current from a 120-volt battery source to a circuit leading to the office B, as follows: 120 volt battery', armature and front Contact of relay 21, middle winding of relay 25, a composite leg (over the tip conductor) of toll line T, through the network enclosed in box 2G, through the corresponding network 126 at the opposite end of the toll line T, the middle winding of relay 125 to ground at the armature and back contact of relay 121. Relay at the originating end of the toll line does not operate at this time since approximately equal current flows through the differentially connected middle and right hand windings of this relay to ground at the armature and back Contact of relay 121 and at the opposite end of the right hand winding of relay 25. However, relay 125 at the distant end operates and provides a circuit for the operation of relays 113 and 110. The circuit for relay 113, is as follows: battery, winding of relay 113, upper inner armature and back contact of relay 122, armature and front contact of relay 125 to ground, while the circuit for relay is as follows: battery, winding of relay 110, lower inner armature and back Contact of relay 115, armature and front contact of relay t-o ground. The operation of relay 118 by opening the connection between its upper armature and back contact disconnects the sleeve circuit of the multiple jack 108 freni ground through the windings of relay 114, in order to prevent interference in case an outward operator at office B attempts to extend a connection over the toll line in the opposite direction by inserting her plug in jack 108. The operation of relay 110 closes a circuit for making the outward end of the toll line at this office busy. This circuit is as follows: battery,

llt

upper armature and front contacty ot relay 110, upper' make-before-loreak contacts ot relay 115, signals 116, 117 and 118 in series to ground. The operation of relay 11() also closes a Circuit for the lighting of the line lainp 129 associated with the plug` 100 at the inward operators position 1B as follows: battery, upper armature and front contact of relay 110, upper oute armature and hack contact ot' relay 122r` lower outer armature and hack Contact ot' relay 12T, lower' outer armature and hack contact ot relay 128, lower inner armature and hack contact ot relay 127, lainp 129 to ground. The light ing of this lalnp notities the inward operator aty the 1B position that the extension oi a connection is desired on this toll line.

The operation ot relay 11G further cl zse supervisory bridge circuit across the tip and ring,V conductors of the toll line. This hrit'lec including :i winding of relay lil may be traced as follows: troni the tip conductor, through the upper winding of re tardation coil 131, upper outer armature and nach contact ol relay 132, lower armature and t'ront Contact ot relay 11G. lett hand winding of relay 13o. lower windingy ot retardation coil lill to the ring' conductor. The purpose ot this bridge for supervisory Vfunctions will he apparent as the description proceeds, The operation of relay 110 also closes an energizing circuit for relay 13 front battery at the uper arniature an-l Yl'ront contact ot this relay through the uppe,l outer armature and 1nach contact of relay 122, lower outer arnriture and hack contact ol relay 12T, lower winding of relay 12321 tc ground. The operatior or" relay 15.23 closes connections at Iits armatures and front contat/ts to a call sequence circuit, indicated with a box 1-1'3 and which is of the well known type tor assigning` the inward operator`s telephone circuit to busy toll lines in succession. The actual connection ot the operators telephone circuit to this toll line will he described later. r111e last' action produced by the oilc eration of relay llt) ii: the closingof a circuit Al'or relay 135` as i'ollows: battery, upper armature and front contact o relay llt), upper outer armature and hach contact ol' relay 122, lower outer armature and back contact oi relay 12T, upper outer armature and hach contact ot relay 12in', upper winding' oi" relay lf'i to ground. The operation ol' relay 13o prepares a connection at its armatures and trout contact` troni a source ot' tone current 1211i to the tip and rinf; conductors oi the toll line and :i tone l'roin this Source therefore now niit'ied over the toll line 'l to tlr originating' ope altor at position 0l); in oiiice A to indicate to this operator that the call has heen registered at the inward operitoii position 1B at ollice B and that the operator transat this latter otlice is not yet free to answer the all.

lfhen the inward operator at 113 is a failahle for the call on this particular toll line, the call sequence circuit 141?) such as shown and descrihed in No. 1,578,651, granted lllarch Si), 192.5, to lol. M. Feiner, tunctions and turnishes a connection to gri/und over lead 1ST tor the operation ot' relay 1255, as thin` le'ifl is connected to one terminal ot the winding ot relay 12E- while the other terminal is connected t( battery. fn: relay 12o ope artes, the circuit for relay ,-5 is liroltcn :xt the upper outer armature and haeltV contact ol relay 12S and consceouently relay 1235 is released and the tone supplied to the originating operator is reniored troni the toll line which now transferred to the 1B opcratoi"s tdephone set at the inner upper and lower ar1nature:-

nl' rrlay 128. The reinora` ot the tone troni tlfe toll line indicates to the originating op era'tor that the distant operator iu ready lo answer.

ri'lz-e operation of reliy 12S also lire dis the energizing circuit for ianip 129 at the lower cr armature and hach' contact ot relay and transfers the circuit for the lamp ough an interrupter 111 to 1oattery at the ront contact of this armature. so that the np 129 will now he alternately lighted d extinguished to indicate to the iuwarl rator that her telephone set connected .his particular toll line. The originating operator now trarnsniits the details of the call to the iuwnrd operator, who then insert dug (lt) into jack 1 1, assuming that the i iect'ion deci? o lic extended over a rinei own toll l o the desired Subscriber, "he condition o the sleeve circuit` on a ringdown toll line it idle is such to cause the operation ot relay 14172 and marginal relay 1351 over the liollowll circuit: from battery upper outer arniatilrc and hach contact olI r day lil). winding o i niargrinal relay lll, win ng ot relay 112, slecie terininals of plugiv l) and vlack 101 to ground on the sleeve o rthe rincdown toll The operation ot relay 112 cioes au line.

follows:

ut 2S i. il

nl, l Y

li t) ol relay 140, upg" winding' of relai7 armature and iront contact ot' i12 to grroun'l. y[he oper: tion of relay transfers the tip conductor ot' the toll 'i from the usual busy te-t lead flirfiugh a); 1111) and jacl-L 101 to the tip condor of the toll line lili?. lt also connects tie ring,v con-:hictor from the toll line 10:2 through the jack 101 and plug 10o to the toll line '1". Si further action on the part ot relay 12T is to open the circuit for lanip 129 troni the interrupter 141 so that this lamp now er;- tinguished.

llo

.sil

The operation of relay 127 also opens the circuit tor 133, which now returns to normal and on the release of relay 133 the ground from the call sequence circuit at 143 ior the operation of relay 128 is removed, so that relay 128 is now also released and the inward operators telephone set is, therefore, set 4free from this particular toll line and will be automatically connected to some other toll line on which a call may be waiting, in accordance with the well known functioning of call sequence circuit at 143.

The operation of marginal relay 139 provides a circuit for the operation of relay 132, as follows: battery, upper inner armature and back contact of relay 140, winding ot relay 132, lower armature and front contact otI marginal relay 139 t0 ground. This marginal relay also opens at its upper armature and back contact a point in a circuit for the lower winding of relay 121, the purpose ot which will hereinafter be described. Relay 132 opens the bridge circuit across the tip and ring conductors the toll line at its upper outer armature and back contact; this bridge having previously been closed at the operation of relay 110, but as it is not needed in this type of connection the purpose of relay 132 becomes clear.

The inward operator may now ring the ringdown toll line operator at the distant end by the operation of key 144 and when this key is operated ringing tone is transmitted over the toll line T back to the originating operator, as an indication that the connection is being established. The circuit from the tone source 145 is connected to the tin and ring et the toll line at the makebe'fore-break contacts of' key 144. The originating operator new listens in to Jfollow the establishing ot the connection and when the called subscriber answers the connection between the calling and called subscribers may be established in the usual manner.

lf the originating operator desires for some reason or other t0 rering a wanted subscriber, she may operate the ringing key associated with her toll cord in the usual manner, which transmits ringing current over the toll line to otiice B and operates alternating current responsive relay 146 at the oliice B, which is bridged across the tip and ring conductors ot the toll line, as follows: tip conductor, through the network 126` winding of relay 146, lower armature and back contact of relay 114, network 126 to the ring conductor. The relay 4G at office A normally bridged across the toll line does not operate at this time since the bridge circuit therefor is open at the lower armature and back contact of relay 14 which it will be remembered is held operated at this time in the sleeve circuit of the originating operators cord. Relay 146 in operating closes a circuit for relay 147 as follows: battery,

Leaaoos winding of relay 147, arn'lature and [ront contact of relay 146 to ground. The operation ot relay 147 causes ringing current to be transmitted over the ringdown toll line to the called subscribers bell. During this ringing interval relay 147 closes its upper outer armature and front contact so that ground is connected to the right hand winding et' relay 130. Relay 130, in turn, closes a circuit through the lower winding of relay 121 whereby the source of 120 volt current is connected to the junction point between the middle and right hand windings of relay 125 and has the etiect of causing the actuation ot relay 25. This is caused by the tact that at this time a source of 120 volt current is connected to the junction point between the middle and right hand windings of relay so that no current now iows over the line and the middle windings ot' relays 25 and 125, but current does flow in the right hand windings of both of these relays. Thus, relay 125 will be maintained energized and relay 25 will become energized. Upon the energization et' relay 25, a circuit will be established from ground, the contact and armature ot relay 25, the back contact in the inner upper armature ot relay winding of relay 13 to battery, causing the encrgization of relay 13. The sleeve circuit which is closed through the back contact and upper armature of relay 13 is, during this interval` maintained closed by the front contact and inner upper armature of relay 15. However, the ground connection through the low resistance winding of relay 14 is opened so that the resistance ot the circuit for relays 11 and 12 is materially increased, whereby relay 12 releascs its armature and completes a circuit for signaling lainn to indicate to the operator, who is depressing her ringing key, that the apparatus at the distant end is operating propcrly` Vhen the originating operator receives a disconnect signal, as the calling subscriber hangs up his receiver, she removes plug 1 from jack 2, and relay 14 releases which causes relay 21 to release. When relay 21 releases, current from the volt battery is disconnected from the composite leg so that relay at the distant end of the toll line at oiiice B will now release. This relay 125 in releasing opens the circuit tor relays 110 and 113. causing them to release. The release ot relay 110 opens the circuit tor the busy signals 116, 117 and 113 and also opens the circuit tor the bridge including relay 130. although this circuit is already disconnectod trom the line by the operation ot relay 132 as hereinbefore described. Relay 110 also closes a circuit Jfor relay 140 as follows: battery, upper armature and back contact ot relay 110, lower make-before-break contacts of relay 140, winding of relay 14() lill lil

to ground at the armature and front contact of relay 142. The. operation otvrelay 140 closes a circuit tor lamp 129 as follows: battery, upper inner armature and front contact of relay 140, lower inner armature and Jfront contact ot relay 127, lanip 129 to `ground. 'the lighting' ot this lainp notities the inward operator at position 1B that the operator at the originating por` tion has disconnected and that this operator may now remove plug,l 100 troni jacl: 101. This relay 110 also transfers the circuits tor relays 139 :2nd 142 to battery, through relay `148 so that this relay now operates in series with relays tilt) and 142 and as relay 11() has released battery \\ill be furnished to relay 12T through its lower winding;` in place of the battery for its upper winding` formerly furnished at the upper inner armature and back contact of relay 140. Under 'these conditions relay 139 inay release but relays 142 and 148 will remain optratcd and relays 121 and 140 will also remain operated on the ground furnished by the operation of the armature of relay 148. rllhe purpose of includingr relays 148 in this sleeve circuit will lio hereinafter described in connection with circuits extending' to other connecting cir- 'uitsx It the inward operator new renioyes plug' 10() 'troni jack 101 relays 12T, 14S and 14() are released and the ringidown toll line operator will new disconnect her cord from the ringdown toll line and iroin the called subscribers line.

lt a connection oy yr the straightforward toll line 'l` is desired to a subscriber' that inay be reached through a switching' trunk such as 11i-1, the. inward operator position 1B inserts plug 1(10 in jack 103. 'l'he particular switching trunks through which a connecti-.in to be extended may be selected by the usual call wire method well linown in the art. Relay 142 will non' operate, but marginal relay 1559 does not operate due to tne resistanre conditions on thc sleeve oi' the switching trunk. llelay 112 in operatingr provides an energizing circuit for relay 12T as preriously traced, causing relay 12T to operate to connect the tip and ring et' plug' 100 to toll line T; to extinguish lanip 129, and to release relay 133, as hereinbe-` 'tore described. lelay 133 in releasing disconnects ground troni lead lli' so that the relay 12H is now also releaf-id l1`he inward operatofs telephone set is, therefore, treed troni this particular connection and will be automatically connected to seine other toll line on which a call niay be waiting.

lillu-n the distant end o't the switching trnnhr 1111 i--1 connected to a subscribei"s line, hrtter'v and: ground will be connected to this trunk, as is well known in the. art, causing;l the operation ot relay 13()` which it will be remembered is included in the bridge across the tip andring conductors ot' the toll line.

An obvious circuit will then be closed by the operation ot relay 13() for the operation ot' relay 121, which now connects the 120 Volt battery, to the middle winding of relay 1257 over the coniposite leg to the corresponding winding ot relay at the originating end. llniler there conditions practically no cui'- rent tlows over the composite leg since a 120 volt battery is connected at both ends thereof and relay will therefore operate over a circuit 'troni these 120 Volt batteries to ground through its right hand winding. Relay 25 in operating closes a circuit for relay 13, while relay does not operate at this tinic since relay already operated, as previously described. Relay 13 in operating` disconnects ground troni the lower low resistance winding oi relay 14, but this relay remains operated through its upper winding'. The resistance of the sleeve cir` cuit to Zground through this winding' of re lay 14 is now of such value as to release the usual marginal relay 11 in the originating operatorie, cord circuit, thus causing her supervisory lamp to light to indicate that the toll line T has been connected to a sifitchingg; trunk.

The oriL Litin;4 operator at position GB now rings the called subscriber connected at the opposite end ot the switching trunk by operating' the usual ringing key in the cord circuit used in this connection. This appli s ringing current oyer the toll line 'l`, which causes the operation ot relay 146 in oliice B while relay 46 at the origginating end does not operate at this tiine since it disconnected troni tl c circuit at the lower arnia ture and back contact ot' relay 14 which is operated at this time. Relay 146 in operating provides a circuit for the operation of relay 14T and the operation ot this relay transmits i'ingjinjr current over the switching; trunk. resulting' in the ringing' of the called subfrribeas bell. Relay 14T also provides at its upp er outer armature and front contact a holding circuit or relay 123() during' thc ringing' period.

`When the called subscriber' answer--', battery and `nourrit previously lnei'itioned as connected to the switching' trunk will be removed, thus causing the release ot relay illu, which in turn releases relay 121, which now opens the circuit supplying battery Yi'roin the 120 yolt source to the composite leg at the armature and iront contact of this relay. ythis renioyal of the current troni the coinposite leg causes the relay 25at thi` ori 5'inatine' end ot the toll line to release, since equal currents are now tlowingy through its two windings. The release ot relay 25 causes the release ot' relay '3. This latter relay now connects ground to the lower windingr ot relay 14 and the resis ences of the two windings ot this relay are ot such Value that the iarginal relay 12 in the originating ltlS lll?

operators cord circuit operates to extinguish the supervisory lamp thereat, thus notifying the originating operator that the called subscriber has answered and that the connection may be completed between the calling and called subscribers.

llvhen at the termination of the conversation between the subscribers the called subscriber replaces the receiver upon the switchhoolr, battery and ground are again connected to the switching trunk 101, causing relay 121() to again operate. The operation of this relay now closes an obvious circuit for the operation ot relay 121 and this relay 121 in operating closes the circuit for current from the volt battery to the. composite leg to canse the operation ol relay This relay in operating causes the reoperation of lamp 50 in the manner hereinhefore described, and this` signal now serves as an indication to the originating operator that the called sul'iscriher has hung up his receiver.

1f the called subscriber instead of hanging up his receiver permanently, moves his switchhooh up and down, to recall the originating operator, it will be seen that the supervisory lamp 50 will be correspondingly lighted and extinguished.

If the originating operator disconnects, relay il releases, which in turn causes the release of relay 21 and if the connection to the called subscribers line is still intact and the called subscribers receiver' is on the hook, relay 15 will remain operated since it is locked up under control of the rela y 25 as this relay remains operated due to the operation of relay 121 as hereinbefore described. The holdingl of relay 15 operated prevents a false signal from appearing at the inward cord 11% of the toll line at the office A; that is, relay l0 will be, prevented from operating at this time and consequently lanip 2) will not light as it ordinarily would "when relay 1:21 is operated, liowever` relay will release as soon as relay 21 releases even though relay 121 is operated as current from the 120 volt battery will he aixiproxiniately equally divided between the middle and right hand windings of relay and since these windings are ditlerentially connected this relay releases. Relay 125 in releasingr opens the circuit for relays 110 and 113 which then release. The release of relay 110 releases the busy signals 110, 11T and 118 and opens the circuit for relay and furnishes battery for the operation of relay 140. The opening of the circuit for relay 130 transmits a disconnect signal to the toll switching trunk at the distainty oll'ice. so that the operator at this end ot the sw'itching trunk will be notilied that an originating operator has disconnected in a manner well known in the art. The operation of relay 1-/10 closes an obvious circuit for signal lamp 129 which in lighting now notities the operator at 1B that the originating operator at OB has disconnected. The inward operator now removes plug 100 from jack 103 and the associated relays return to normal. It should be noted that in this case the method of transmitting a disconnect signal is different from that employed in ringdown toll line connection as previously described but relays 130, 139, 142, and 147 while functioning in the same manner as before do not have the same effect on the switching trunk circuit as they did on a ringdown toll line. Vhen relay 130 releases on the release of relay 110 relay 121 will also release and therefore relay 25 will release and cause the release of relay 15 so that the circuits at the outward end of the toll line T will now also be restored into normal condition.

In case the extension of a connection from the toll line T requires a built-up connection including two or more straigl'itforward toll lines, such as toll line T, the inward operator at position 1B will insert her plug 100 in jack 105 of the two-way straightforward toll line 106 and the functioning of the circuits are the same as when a connection is eX- tended through a ring down toll line, i. e., relays 139 and 142 are operated and the apparatus at the outgoing and incoming' ends of the second straightforward toll line then function the same as the first straightforward toll line, up to the point where the called subscribers line is seized. At this time the sleeve resistance ot' the outward end of this second straightforward toll line circuit. 106 is changed in the same manner as the sleeve resistance was changed on the operation of relay 13 when plug 100 was inserted in jack 103 of a switching trunk so that relay 139 is released. This relay in releasing provides a circuit tor the operation of relay 121V as follows: battery, lower winding ot relay 121, upper armature and back contact of relay 13S), lower arn'iature and t'ront contact` of relay 132 to ground. The operation of relay 121 causes, as hereinbefore described, the operation of signal 50 at the originating operators cord circuit to indicate that the connection has been extended to the called subscribers li'ne. The originating operator may now ring the called subscriber in the same manner as when a connection was established over the first. straightforward toll line T only. Under this condition the ringing current is transmitted to cause the operation of relay 1117, which transmits ringing current` over the second toll line to cause the operation of a relay similar to 14T. which results in the ringing of the called subscriber in the same manner as lic-reinbefore described. Then the called subscriber answers, ground is connected to the lower winding of the relay in the second toll line corresponding to relay 114 of the tirst dit llt)

straightforward toll line T in the saine manner as hereinbefore described and under this condition the sleeve resistance will be such as to cause the operation of relay 139 of the first straightforward toll line and the operation of this relay causes, as hereinbefore described, the extinguishing of lamp o() at the originating operators position to indicate that the Called subsc 'iber has answered. Therefore, in connections of this type, that is, where more than onev straightforward toll line is used, complete switchhook supervision will pass t the originating operator through the various straightforward tol lines and wlien thc subscriber disconnetts thi` functions of these straightforward toll liuc circuits will be the saine as the function described in connection with the disconnect signal incoming through a switchingl trunk.

When the originating operator remove; plug 1 from jack 2 while the plug 100 at the distant en'd'isconnected to jack 105 of another straightforward trnnlf, relay 140 of the first trunk becomes operated as hereinbefore described, whereupon relays 142, 139 an'd 148 are included in series with the sleeve of plug 100. Relay 148 is of high resistance, so that relays 139 and 142 release. The latter relay, while not being adjusted to release in the saine manner as relay '139, is also marginal. The armature and front contact of relay 14178 now substitute for the arniature and front Contact of relay 142. Due to the high resistance of the sleeve circuit of plug 100, the relay of the straightforward trunk'corresponding to relay 114 is released, whereupon a disconnect signal is given to the distant end of the second straightforward trunk in the lnanner hereiuliefore described.

when the inward operator at position 1B receives a call requiring a connection cxtending through a repeater. this operator will. instead of inf-:erting her plug.I ltld into jacks such as 101, 103, and 1o.?, nioinenar depress kf 1E() associated with this` toil li 'lhc operation of this key cli'iscsl an obvious circuit for the operation of relay itil. which in turn closes a circuit for relay 122. rl`his latter relay provides a locking` ci cuit 'or itseltl to ground at the armature :uid trout contact of relay {elay 151 in operating connects battery. furnished through the opt-rated relays 11() and 122 for the otl line lanip 152 associated with jack 107 at the repeater operators position. The cir inc.'

i cuits are as follows: battery. upper arniature and front contact of relay 110, upper outer arn'iature and front contact of relay 122, lower arniature and front contact oi relay 151, lamp 152't0 ground. The lighting' of this lainp notifies the repeater operator at this position that a connection through a i'i'peater froni this particular toll line is desired. Relay 122 in operating' also releases relays 113 and lf3?) and closes a circuit for the operation of relay 135, as folldws: battery, upper armature and front contact of relay 110, upper outer armature and front contact of relay 122, lower winding of relay 135, to ground. Vl'hen relay 135 releases, relay 128 is also released and the telephone set of the operator at' position 1B is disconnected and lainp 12S) extinguished. Relay 135 in operatingl sends the tone back to the originating operator at position GB, indicati-- ing to tl at operator that the call has been' transfcrrcd to the repeater operator.

The repeater operator seeing lanip lf2 lighted answers the call by inserting the plug of thc repeater cord (not shown) into cli T associated with this lennp 152. This causes the operation of relay 114 and the operation of this relay closes a circuit for relays 115 and 120. yl`he operation of relay 112i pr vides a circuit for holding the busy signals 116, 11T and 118 operated while it causes the release of relay 110. Relay 115 also cs-:tahlishes holding' circuits for relays 122 and 151 h v closing its lower outer arinature to the corresi'ioiuling front contact and ground of relay 114- so that in case the originating operator disconnects before the repcating operator has disconnected these rclays will not rele-.isc but pcrforni certain functions that will bc hereinafter described. Relay 115 in operating also locks up under the control of relay 125, in order to prevent relay 110 from operating and cause certain operations at the inward operators position 1B in oase the r peuter operator disconnects before the riginating operator disconnects as will hereinafter he described. Relay 1215 in operating transfers the tip and ring conductors of the straightforwarel toll line 'l' from the cud of the circuit terniiruitiiucI at the inward opcrator-s position l" t il* i.) .o thc 1th' of the repeater operatonsl position and also clorcs thc circuit 'or thc u'ipcr winding of relay 121. lint this relay docs not opcratc at this tinte as relays lll and l arc operated. The release ot' relay llt) opens the circuit vfor thc lanip 1532 at its upper arn1ature and front Contact and causes thc release of relay 135 to disconnect the tone from thc toll line, The connection now ready for the extension through the repeater operato1"s position.

If a connection is desired through a dolaycd operators position. the key 155 is nionientarily operated and the operation of this liey closes the energizing circuit for rela)v 122, which locks up unile control of ground at relay 12:. he operation from this point on is the sani-e as that described in connection with the extension through to the repeater operators position, except that relay 151 is not operated, and consequently lainp 15G lighted in place of lainp 152 and the delayed operator inserts the answering plug of one llil of her cords in jack 108 so that the extension of the call will then be through this operators position.

The functions of the circuits when calls are completed through a repeater operators "f by reringing as in the case of a repeater connection.

lllhen the originating operator disconnects, relay 14 releases so that relays 15, 2O and 21 are in turn released and so that the circuitfor relay 4G is closed. Relay 20 in releasing transfers the toll line T from the outward end to the tip and ring of the inward end of the toll line equipment at oiiice fr. The release of relay 15 releases the busy signals 16, 17 and 18 and closes the circuit for relay 10 to the front contact of relay 25. Relay 21 in releasing opens the circuit from the 120 volt battery, thereby releasing relay 125 at the distant end of the toll line. lf this release of the connection by the originating operator takes place before a repeater operator disconnects, relay 125 in releasing will not release relays 115, 122 or 120, as these relays are locked up under control of relay lll, as liereinbefore described. Therei'ore, as relay 122 is operated, relay 121 cannot operate and cause a false signal to be set up at the inward position 1li' as would ordinarily take place in case a connection was desired trom otlice l to oltce A plug inserted in jack 109 or as in this case in jacl; 10T or 108 would cause the oran-ation of relay 11 which would result in the operation ot' relay 121. lt is, therefore, seen that even though a connection is made through a jack at the outward position of otiice l no signal is received at the inward position at otlice A under these circumstances. `When now the repeater operator disconnects relay 114 releases and consequently all the other relays release and the circuits are restored to normal.

lt is evident that the circuit functions in the same manner in the case of a connection through a delayed operators position when the origimlting` operator disconnects before the delayed operator, except that in that ease relay 151 is not operated, as would be the case when a repeater operator is connected to the circuit.

ln case the repeater operator disconnects before the originating operator disconnects, a disconnect signal is transmit-ted to the originating operator as follows: Relay 11iY releases as soon as the repeater operators plug is removed from jack 107 and a circuit is completed for the operation of relay 121 from the ground at the upper armature and bach Contact of relay 114 through the lower armature and front contact of relay 122. This relay 121 in operating connects the Circuit from the 120 volt battery over the composite leg for the operation of relay at the originating end of the circuit at otiiee A. Ythe operation of this relay closes a circuit tor relay 13, as hereinbefore described, which in turn opens the circuit to ground for the lower winding of relay 14. The resistance ol' the sleeve circuit is now such as to cause the release of the marginal relay 12 at the originating operator-s cord circuit and lamp .7() is therefore lighted as a disconnect signal.

lt will be noted that the relay is locked up under control of relay 125 to prevent relay 110 from operating, so as to prevent a 'false signal appearing at the inward operators position 1B in office B, even though the originating operators plug 1 is still inserted in jack 2 at this time, which would ordinarily cause relay 110 to operate and the lamp 129 to light to indicate to the inward operator at this oliice that a connection desired.

Vhen the originating operator disconnects, relay 125 is released, which in turn releases relays 151, 122, 120, 115 and 121, restoring the circuits to normal. The circuits under these conditions operate in the same manner as they do in case a` delayed operator disconnects before the originating operator disconnects, except that, of course, relav '151 is not operated.

lVhat is claimed is:

1. A two-way trunk line terminating at `,ach end in outward and inward terminals. a signal at each inward terminal responsive to a connection established over a distant outward terminal, means associated with the inward terminals for signaling outward terminals at the same end of the line whereby a connection may he established from an outward terminal at one end of the line to the inward terminal at the other end of the line and then transferred to an outward terminal at said other end of the line and means responsive to such a connection from an outward terminal at one end to an outward terminal at the other end of the. line to prevent the inward terminal signal at either end from being actuated when disconnection takes place at the opposite end,

2. A two-way trunk line terminating at each end in outward and inward terminals, a signal at each inward terminal responsive to a connection established over a distant l tlf) lli fill

outward terminal. means associated with the inward terminals for signaling` outward terminals at. the same end of the line whereby a connection mayv be established from an outward terminal at one end ot' the line to the inward terminal at the other end ot the line and then transferred to an outward terminal at said other end ot the line, and means responsive to such a connection from an outward terminal at one end to an outard terminal at the other end of the line to prevent the inward terminal signal aty the end to which the connection was established trom being actuated when disconnection at the outward terminal from which the connection was established takes place before the disconnection at the other outward terminal. I

Ii. A two-way trunk line terininating at cach end in outward and inward terminals, a signal at each inward terminal responsive to a connection establish-ed over a distant outward terminal, means associated with the inward terminals for signalingl outward terminals at' the same end ot' the line whereb v a connection may be established from an outward terminal at onel end of the line to the inward terminal at the other end ot' the line and then transferred to an outward terminal at said other end of the line and means responsive to such a connection trom an outward terminal at one end and to an outward terminal at the other end ot' the line to prevent the inward terminal signal at the end l'rom which the connection was established from heilig actuated when disconnection at the outward terminal to which the connection was established talles place before the distounection at the other outward terminal.

l. A trunk line having at its inward end means including a signal. a bridge circuit acrossy the talking conductors ot the line. and means for changing the electrical characteristics ot the sleeve conductor at the inward end oli the line characterized by the provision of means responsive to disconnection ot a connection at the outward end of the line for simultaneonsl)v actuating the signal. tor opening' the bridge and changing the electrical characteristics ot the sleeve conductor thereat.

5. A two-wav trunk line terminating at' each end in outward and inward terminals. a signal at' each inward terminal responsive to a connection established over a distant outward terminal. and means associated with the inward terminals ot said line tor reoperating said signal at the inward terminal at one end of said line and for changing the electrical characteristics ot` the` inward ter minal at the same end of the line responsive when disconnection takes place at the opposite end of said line.

A two-way trunk line tern'iinating at each end in outward and inward terminals,

a sional at each inward terminal responsive to a connection established over a distant outward terminal. and means associated with the inward terminals of said line for reoperating raid signal atr the inward terminal f om` end oi the line. Ytor opening a bridge circuit across the talking conductors ol the iiue at the inward terminals at the same end ol the line and i'or changing the elec trical charactcrhtics ot' the sleeve terminal ot said inward terminals at the same end ot' the line respon ive when disconnection takes place atr the opposite end of said line.

i'. i two-wa);v truuk line terminating at each end in outward and inward terminals. a signal at the inward terminals responsive to a connection established over a distant, outward terminah and means associated with the inward terminals ot' said line for operating said signal at the inward termiVV nais ot' one end ot the line. tor opening a bridge circuit across the talking conductors ot' the line at the inward terminals at the same end ot the line and tor changing the electrical characteristics of the sleeve terminal ot' said inward terminals` at the same end ot' the line responsive when this connection 'ues place at the opposite end ot' said line.

H. A two-wav trunk line terminating at ach end in outward and inward terminals. a yignal device at each inward terminal. means associated with the outward termi nais responsive to a change in the electrical characteristics otthe sleeve terminals thereot tor transmitting a signal over said line to the inward terminals at the opposite end ot the line. and means associated with the in ward terminals responsive to said signal received over the line t'or operating the signal device :at thev inward terminals at the opposite end ot the line and for simultancousl)v e:--zt'abli;-fhinf a corresponding change in the electrical characteristics ot the inward sleeve terminal at said opposite end of the line.

l). trunk line, having at its outward end means ter transmitting a signal to the in-V ward end and tor operating a signal device at the inward end on a certain change in the electrical cha 'acteristics of the outward end when a connection is. established to said outward end ol` the line char: 'terized liv the provision ot' means responsive to the disconnection oi" a connection at the outward end tor reoperating said signal device and est-ablishing a correspomling change in the electrical characteristics at the inward end ol the line.

lo. two-way trunk line terminating at each end in outward and inward terminals. means tor est ablishing a connection between an outward terminal at. one end to the in 'ard terminal at the opposite end ol the line. means associated with the inward terminals 'for signaling the outward terminals l l t) at the same end of the line, whereby a connection established to this inward terminal may be transferred from said inward terminals to said outward terminal at the same end, means for signaling the outward termisaid last mentioned signaling means on the establishing of a. connection with the outward terminal to which a connection from the connection originating end oi' the line was transferred.

In Witness whereof, I hereunto subscribe my name this 27 day ot' June A. 1)., 1925.

ERMY R. SMlTH. 

